A simple device for inflating the inner tube of a bicycle, motor vehicle etc., is illustrated and described in U.S. Pat. No. 2,575,908. This device incorporates a gas cartridge with a neck which is closed internally by means of a metal diaphragm. The cartridge neck has an internal screw thread by means of which it can be screwed to the external threads of a conventional valve connector or adaptor of a motor-vehicle inner tube. Arranged in the cartridge neck is an axially displaceable pin which when the neck is screwed onto the valve adaptor is moved towards the diaphragm and punctures the same. One drawback with this known device is that the whole of the cartridge is emptied at one and the same time, and that it is impossible to control the filling of the inner tube with gas.
Devices which utilize gas cartridge and intended for other purposes are known from U.S. Pat. Nos. 2,349,480, 2,673,004 and 3,051,356. In these devices the gas cartridge is enclosed in a housing, but in general has the same drawbacks as the device described in the aforegoing.
One object of this invention is to provide an inflating device which comprises a minimum of components and that said components can be readily assembled. A further object is to provide an inflating device of the aforesaid kind which (a) can be readily used with one hand, (b) is sufficiently narrow to enable it to be fitted without difficulty to the valve of a bicycle tire, with closely adjacent spokes, and (c) which requires only a slight pressure to initiate inflation of the inner tube. As soon as this slight pressure is relieved, inflation ceases automatically, so as to enable the tire (inner tube) to be inflated to a desired pressure without emptying the cartridge.